1. Field of the Invention
The present invention relates to a printed circuit board for a mobile platform, and in particular, to a routing arrangement of ground traces and signal traces of a printed circuit board for a mobile platform.
2. Description of the Related Art
Printed circuit boards (PCBs) are used to mechanically support and electrically connect electronic components using conductive pathways, conductive traces (e.g. signal traces or ground traces) etched from metal sheets laminated onto a non-conductive core substrate. For a semiconductor chip package design, an increased amount of input/output (I/O) connections for multi-functional or memory chips is required. The impact of this will be pressure on printed circuit board (PCB) fabricators to minimize the width and the space of the conductive traces, or increase the number of layers on the PCB. The increased amount of conductive traces needs to be arranged in different layer levels of the PCB. However, the conductive traces arranged in different layer levels of the PCB result in an impedance mismatch problem between the electronic components and the conductive traces in different layer levels, especially in high signal speed applications, for example, mobile platform applications. The impedance mismatch problem can detrimentally affect the shape of a signal traveling on a conductive trace, thereby affecting the signal reception of the electronic component supported by the PCB. Also, signal traces with small spaces therebetween can result in a crosstalk problem.
Thus, a novel printed circuit board for mobile platforms is desirable.